Add a `readable` property to `fs.File` objects exposing a readable stream

[oleiade]

With version v0.48.0 k6 introduces the k6/experimental/fs module and the ability for users to open and read from files in a normalized and efficient manner.

Solution space

We aim to benefit from our ongoing implementation of the Streams API within k6 to pursue adding a .readable property to fs.File objects. In the same fashion as Deno does, that property would return a ReadableStream of the file's content to the user.

Using it, users would be able to stream the content of the file in a standardized and simplified manner, as opposed to using our currently existing low-level API.

import { open } from 'k6/experimental/fs';

let file;
(async function () {
  file = await open('bonjour.txt');
})();

export default async function () {
	const fileStream = file.readable;
	const reader = fileStream.getReader();

	while (true) {
		const { done, value } = await reader.read()
		if (done) break
	}
}

Definition of done

The fs.File object exposes a readable property which consists in a ReadableStream instance that allows to stream in a read-only and asynchronous fashion the content of the file.